Arcing from electrical power cables at points of worn or damaged insulation constitutes a significant fire hazard in most building environments. This is particularly so in telephone company central offices which may remain unoccupied for considerable lengths of time. Although the DC power supply systems in these locations include protective fuses to ensure interruption of dangerous current flow in the event of a short circuit, the level and duration of the momentary current surge at the instant of arcing are usually insufficient to actuate such fused protection. The heat accompanying such arcing is, however, quite capable of initiating a destructive fire.
There is thus a definite need for a means by which arcing in a damaged electrical system may be detected and an alert or disconnect signal given in time to avert serious losses. The present invention provides such a means through recognition of the characteristic frequency domain energy distribution pattern generated by the arcing itself. By continually monitoring the power supply system for the appearance of such a pattern, the invention is able to provide early warning of a hazardous arcing condition.